1. Technical Field
The present application claims priority to Korean Patent Application No. 10-2016-0021750 filed on Feb. 24, 2016 in the Republic of Korea, the disclosures of which are incorporated herein by reference.
The present disclosure relates to a motor drive unit. More specifically, the present disclosure relates to a motor drive unit in which circuit boards can be assembled more easily, and the circuit boards are shielded from foreign matter to improve quality reliability and durability of the circuit boards, with reduced size to save the cost.
2. Description of the Related Art
Typically, a motor drive unit refers to a series of apparatuses that receive power from the mains electricity to vary the voltage and frequency by itself and control the speed of a motor with high efficiency.
The demands for a motor drive unit are ever increasing as means for saving energy and improving the energy utilization efficiency.
Such an existing motor drive unit will be described below.
FIG. 1 is a perspective view of an existing motor drive unit. FIG. 2 is a perspective view of an existing power PCB assembly. FIG. 3 is a side view of an existing motor drive unit.
Referring to FIGS. 1 to 3, an existing motor drive unit includes a heat sink 1, a middle base part 2, and a plurality of PCB assemblies.
The heat sink 1 is installed on a base.
The middle base part 2 is disposed on the heat sink 1. The middle base part 2 is coupled with the heat sink 1 by hooks 6.
The area of the middle base part 2 is substantially equal to the area of the upper portion of the heat sink 1.
In the middle base part 2, the plurality of PCB assemblies is installed.
The plurality of PCB assemblies includes a power PCB assembly 3, a condenser PCB assembly, and a control PCB assembly.
On the upper portion of the middle base part 2, the power PCB assembly 3 is installed.
Although not shown in the drawings, the condenser PCB assembly and the control PCB assembly are disposed on the upper portion of the power PCB assembly 3.
The arrangement and effects of the above-described configuration will be described in detail below.
The middle base part 2 disposed on the heat sink 1 is coupled by a hook 7.
The middle base part 2 fastens and couples the plurality of PCB assemblies and isolates the heat sink 1 from the power PCB assembly 3.
The power PCB assembly 3 is coupled on the middle base part 2 by the hooks 6 and screws.
The heat sink 1 discharges heat generated in a module in the power PCB assembly 3.
The condenser PCB assembly is coupled with the power PCB assembly with screw holders 10 of the power PCB assembly and bosses 11 of the middle base unit 2 and coupled with the hooks 7 of the middle base part.
The screw holders 10 may fix the condenser PCB assembly and may allow a current to flow from the power PCB assembly 3 to condensers.
In the existing motor drive unit having the above-described configuration, the condensers 12 are mounted above the condenser PCB assembly.
In the existing motor drive unit having the configuration, the heat sink has the area equal to the area of the middle base part. Therefore, the size of the heat sink is determined based on the overall size of the product, not on the optimal size for discharging heat generated in a module, such that it is difficult to reduce the size of the apparatus.
In addition, the larger the size of the apparatus is, the larger the size of the heat sink is, and thus there is a problem in that the price of the apparatus is increased.
In addition, the condensers 12 disposed on the power PCB assembly 3 are mounted only on the upper side of the board, and thus the height of the apparatus is increased with the height of the condensers 12. Therefore, there is a limit on reducing the size of the product.
Moreover, in the existing motor drive unit, the hooks 6 in the middle base part are fastened to the heat sink 1, and thus durability is lowered and it can be easily broken by external force.
For example, Korean Patent Publication No. 10-2007-0053940 (published on May 28, 2007) discloses a flexible circuit board that prevents circuit interference between layers.